Conventional vaginal contraceptive products utilizing a spermicidal agent provide a very limited duration of contraception. Conventional methods of spermicidal contraception require that the products need to be inserted into the vagina not more than one hour preferably 10-30 minutes before coitus for suppository products and even less time for foam and gel products. In view of such time constraints these products must be reapplied if coitus is repeated more than one hour after the original insertion. While various attempts have been made in the art to provide a longer lasting and more convenient vaginal contraceptive spermicidal suppository, they have met with only limited success.
Riley, Jr. et al. in U.S. Pat. No. 4,551,148 describe a vaginal delivery system which is allegedly bio-adherent to the vaginal surface and releases an active agent in a controlled manner for at least three hours to a receptor site. Foamable-type vaginal suppository compositions have also been developed, but such have not been found to provide effective contraceptive activity for long periods of time.
It is therefore an object of the present invention to provide a novel vaginal contraceptive suppository which has a long period of contraceptive activity and is highly effective in preventing conception due to coitus for up to 12 hours after initial insertion of the suppository.